Please Help for PA Fubar 12" (I need it)

Hello to all of autosound and voice pressure lovers. I am from Ukraine, that in Europe. Noticed that many of you had Power Acoustik FUBAR 12”. Please, prompt me, help to build a box for him vented. I very ask, you have more experience, I know that loud speaker not very much good, but on greater I do not have a money.
The instruction is not aviable, cubic feet I don’t know what is.
Please! Help.
PS - I want to have so many Db, how it possible, for Ukraine it is a good speaker!
I want to show my friends and other people, what is SPL by "USA friends help".